N α‐9‐Fluorenylmethyloxycarbonyl (Fmoc) amino acids will be of advantage in solid phase peptide synthesis. The Fmoc‐group is quantitatively cleaved by mild base (piperidine). This permits the use of tert‐butyl‐type side chain blocking and of peptide‐to‐resin linkage cleavable by mild acidolysis. Side reactions arising from repetitive acid deprotection and final HF cleavage in contemporary solid phase synthesis are avoided. Fully bioactive and homogeneous dihydrosomatostatin was obtained in 53% overall yield.

The utility of repetitive nonhydrolytic base cleavage of α‐amino protective groups in solid phase peptide synthesis is shown by a preparation of the model tetrapeptide leucyl‐alanyl‐glycyl‐valine on a p‐benzyloxybenzyl ester polystyrene–1% divinylbenzene resin support. Nα‐9‐Fluorenylmethyloxycarbonyl (Fmoc: Carpino & Han, 1970, 1972) amino acids were coupled by the symmetrical anhydride procedure, followed by Fmoc group cleavage using 50% piperidine in methylene chloride. Quantitative removal of the Fmoc‐tetrapeptide from the solid support was effected by treatment with 55% trifluoroacetic acid in methylene chloride. Homogeneous free tetrapeptide was obtained in 87% overall yield. The procedure is proposed to offer advantages over present solid phase methods which use acidolysis for repetitive α‐amino group deblocking.

The results obtained to date, in terms of sensitivity as well as specificity, strongly suggest that the PRISM Chagas assay should function well as a tool for screening blood for serologic evidence of T. cruzi infection.